SwiftExpressionParser: link swiftrt to liblldb on linux

[eeckstein]

This is need to let the swiftCompilerModules work properly.

Fixes the linux PR test failures for swiftlang/swift#71723

[eeckstein]

@swift-ci test

[etcwilde]

Do you have a build log/build.ninja for this? The change itself looks fine, but CMake should be using Swift as the linker here, which should be linking swiftrt.o/swiftrt.obj automatically when appropriate so this shouldn't be necessary.

[atrick]

@etcwilde I reran linux tests here:
swiftlang/swift#71723

Presumably that will give you a build log if you grab it in time. @eeckstein may have one locally.

[eeckstein]

I tested this locally. CMake doesn't use swiftc for linking. It's using clang++